Appendix: Periodic Table of the Elements - Introduction to Chemistry: General, Organic, and Biological

In this chapter, we present some data on the chemical elements. The periodic table lists all the known chemical elements, arranged by atomic number (that is, the number of protons in the nucleus). The periodic table is arguably the best tool in all of science; no other branch of science can summarize its fundamental constituents in such a concise and useful way. Many of the physical and chemical properties of the elements are either known or understood based on their positions on the periodic table. Periodic tables are available with a variety of chemical and physical properties listed in each element’s box. What follows here is a relatively simple version. The Internet is a great place to find periodic tables that contain additional information.

One item on most periodic tables is the atomic mass of each element. For many applications, only one or two decimal places are necessary for the atomic mass. However, some applications (especially nuclear chemistry; see Chapter 11 "Nuclear Chemistry") require more decimal places. The atomic masses in Table 21.1 "The Basics of the Elements of the Periodic Table" represent the number of decimal places recognized by the International Union of Pure and Applied Chemistry, the worldwide body that develops standards for chemistry. The atomic masses of some elements are known very precisely, to a large number of decimal places. The atomic masses of other elements, especially radioactive elements, are not known as precisely. Some elements, such as lithium, can have varying atomic masses depending on how their isotopes are isolated.

The web offers many interactive periodic table resources. For example, see http://www.ptable.com.

Periodic table with all 118 official element symbols, atomic numbers, abridged 2024 standard atomic weights, and group numbers. — The periodic table with all 118 official element names and symbols; atomic weights are CIAAW abridged 2024 values. Bracketed numbers are mass numbers for selected radioactive isotopes, rather than standard atomic weights.

An annotated carbon cell shows atomic number 6, symbol C, name carbon, and standard atomic weight 12.011. A separate example [294] is labeled isotope mass number, not standard atomic weight. — Reading a periodic-table cell: the atomic number counts protons; the chemical symbol identifies the element; a standard atomic weight describes a naturally occurring isotopic mixture. Bracketed mass numbers for selected radioactive isotopes have a different meaning.

Table 21.1 The Basics of the Elements of the Periodic Table

Name	Atomic Symbol	Atomic Number	Atomic Mass	Footnotes
actinium*	Ac	89
aluminum	Al	13	26.9815386(8)
americium*	Am	95
antimony	Sb	51	121.760(1)	g
argon	Ar	18	39.948(1)	g, r
arsenic	As	33	74.92160(2)
astatine*	At	85
barium	Ba	56	137.327(7)
berkelium*	Bk	97
beryllium	Be	4	9.012182(3)
bismuth	Bi	83	208.98040(1)
bohrium*	Bh	107
boron	B	5	10.811(7)	g, m, r
bromine	Br	35	79.904(1)
cadmium	Cd	48	112.411(8)	g
caesium (cesium)	Cs	55	132.9054519(2)
calcium	Ca	20	40.078(4)	g
californium*	Cf	98
carbon	C	6	12.0107(8)	g, r
cerium	Ce	58	140.116(1)	g
chlorine	Cl	17	35.453(2)	g, m, r
chromium	Cr	24	51.9961(6)
cobalt	Co	27	58.933195(5)
copernicium*	Cn	112
copper	Cu	29	63.546(3)	r
curium*	Cm	96
darmstadtium*	Ds	110
dubnium*	Db	105
dysprosium	Dy	66	162.500(1)	g
einsteinium*	Es	99
erbium	Er	68	167.259(3)	g
europium	Eu	63	151.964(1)	g
fermium*	Fm	100
fluorine	F	9	18.9984032(5)
francium*	Fr	87
gadolinium	Gd	64	157.25(3)	g
gallium	Ga	31	69.723(1)
germanium	Ge	32	72.64(1)
gold	Au	79	196.966569(4)
hafnium	Hf	72	178.49(2)
hassium*	Hs	108
helium	He	2	4.002602(2)	g, r
holmium	Ho	67	164.93032(2)
hydrogen	H	1	1.00794(7)	g, m, r
indium	In	49	114.818(3)
iodine	I	53	126.90447(3)
iridium	Ir	77	192.217(3)
iron	Fe	26	55.845(2)
krypton	Kr	36	83.798(2)	g, m
lanthanum	La	57	138.90547(7)	g
lawrencium*	Lr	103
lead	Pb	82	207.2(1)	g, r
lithium	Li	3	[6.941(2)]†	g, m, r
lutetium	Lu	71	174.967(1)	g
magnesium	Mg	12	24.3050(6)
manganese	Mn	25	54.938045(5)
meitnerium*	Mt	109
mendelevium*	Md	101
mercury	Hg	80	200.59(2)
molybdenum	Mo	42	95.94(2)	g
neodymium	Nd	60	144.242(3)	g
neon	Ne	10	20.1797(6)	g, m
neptunium*	Np	93
nickel	Ni	28	58.6934(2)
niobium	Nb	41	92.90638(2)
nitrogen	N	7	14.0067(2)	g, r
nobelium*	No	102
osmium	Os	76	190.23(3)	g
oxygen	O	8	15.9994(3)	g, r
palladium	Pd	46	106.42(1)	g
phosphorus	P	15	30.973762(2)
platinum	Pt	78	195.084(9)
plutonium*	Pu	94
polonium*	Po	84
potassium	K	19	39.0983(1)
praseodymium	Pr	59	140.90765(2)
promethium*	Pm	61
protactinium*	Pa	91	231.03588(2)
radium*	Ra	88
radon*	Rn	86
roentgenium*	Rg	111
rhenium	Re	75	186.207(1)
rhodium	Rh	45	102.90550(2)
rubidium	Rb	37	85.4678(3)	g
ruthenium	Ru	44	101.07(2)	g
rutherfordium*	Rf	104
samarium	Sm	62	150.36(2)	g
scandium	Sc	21	44.955912(6)
seaborgium*	Sg	106
selenium	Se	34	78.96(3)	r
silicon	Si	14	28.0855(3)	r
silver	Ag	47	107.8682(2)	g
sodium	Na	11	22.98976928(2)
strontium	Sr	38	87.62(1)	g, r
sulfur	S	16	32.065(5)	g, r
tantalum	Ta	73	180.94788(2)
technetium*	Tc	43
tellurium	Te	52	127.60(3)	g
terbium	Tb	65	158.92535(2)
thallium	Tl	81	204.3833(2)
thorium*	Th	90	232.03806(2)	g
thulium	Tm	69	168.93421(2)
tin	Sn	50	118.710(7)	g
titanium	Ti	22	47.867(1)
tungsten	W	74	183.84(1)
ununhexium*	Uuh	116
ununoctium*	Uuo	118
ununpentium*	Uup	115
ununquadium*	Uuq	114
ununtrium*	Uut	113
uranium*	U	92	238.02891(3)	g, m
vanadium	V	23	50.9415(1)
xenon	Xe	54	131.293(6)	g, m
ytterbium	Yb	70	173.04(3)	g
yttrium	Y	39	88.90585(2)
zinc	Zn	30	65.409(4)
zirconium	Zr	40	91.224(2)	g
*Element has no stable nuclides. However, three such elements (Th, Pa, and U) have a characteristic terrestrial isotopic composition, and for these an atomic mass is tabulated.	*Element has no stable nuclides. However, three such elements (Th, Pa, and U) have a characteristic terrestrial isotopic composition, and for these an atomic mass is tabulated.	*Element has no stable nuclides. However, three such elements (Th, Pa, and U) have a characteristic terrestrial isotopic composition, and for these an atomic mass is tabulated.	*Element has no stable nuclides. However, three such elements (Th, Pa, and U) have a characteristic terrestrial isotopic composition, and for these an atomic mass is tabulated.	*Element has no stable nuclides. However, three such elements (Th, Pa, and U) have a characteristic terrestrial isotopic composition, and for these an atomic mass is tabulated.
†Commercially available Li materials have atomic weights that range between 6.939 and 6.996; if a more accurate value is required, it must be determined for the specific material.	†Commercially available Li materials have atomic weights that range between 6.939 and 6.996; if a more accurate value is required, it must be determined for the specific material.	†Commercially available Li materials have atomic weights that range between 6.939 and 6.996; if a more accurate value is required, it must be determined for the specific material.	†Commercially available Li materials have atomic weights that range between 6.939 and 6.996; if a more accurate value is required, it must be determined for the specific material.	†Commercially available Li materials have atomic weights that range between 6.939 and 6.996; if a more accurate value is required, it must be determined for the specific material.
g Geological specimens are known in which the element has an isotopic composition outside the limits for normal material. The difference between the atomic mass of the element in such specimens and that given in the table may exceed the stated uncertainty.	g Geological specimens are known in which the element has an isotopic composition outside the limits for normal material. The difference between the atomic mass of the element in such specimens and that given in the table may exceed the stated uncertainty.	g Geological specimens are known in which the element has an isotopic composition outside the limits for normal material. The difference between the atomic mass of the element in such specimens and that given in the table may exceed the stated uncertainty.	g Geological specimens are known in which the element has an isotopic composition outside the limits for normal material. The difference between the atomic mass of the element in such specimens and that given in the table may exceed the stated uncertainty.	g Geological specimens are known in which the element has an isotopic composition outside the limits for normal material. The difference between the atomic mass of the element in such specimens and that given in the table may exceed the stated uncertainty.
m Modified isotopic compositions may be found in commercially available material because it has been subjected to an undisclosed or inadvertent isotopic fractionation. Substantial deviations in the atomic mass of the element from that given in the table can occur.	m Modified isotopic compositions may be found in commercially available material because it has been subjected to an undisclosed or inadvertent isotopic fractionation. Substantial deviations in the atomic mass of the element from that given in the table can occur.	m Modified isotopic compositions may be found in commercially available material because it has been subjected to an undisclosed or inadvertent isotopic fractionation. Substantial deviations in the atomic mass of the element from that given in the table can occur.	m Modified isotopic compositions may be found in commercially available material because it has been subjected to an undisclosed or inadvertent isotopic fractionation. Substantial deviations in the atomic mass of the element from that given in the table can occur.	m Modified isotopic compositions may be found in commercially available material because it has been subjected to an undisclosed or inadvertent isotopic fractionation. Substantial deviations in the atomic mass of the element from that given in the table can occur.
r Range in isotopic composition of normal terrestrial material prevents a more precise Ar(E) being given; the tabulated Ar(E) value and uncertainty should be applicable to normal material.	r Range in isotopic composition of normal terrestrial material prevents a more precise Ar(E) being given; the tabulated Ar(E) value and uncertainty should be applicable to normal material.	r Range in isotopic composition of normal terrestrial material prevents a more precise Ar(E) being given; the tabulated Ar(E) value and uncertainty should be applicable to normal material.	r Range in isotopic composition of normal terrestrial material prevents a more precise Ar(E) being given; the tabulated Ar(E) value and uncertainty should be applicable to normal material.	r Range in isotopic composition of normal terrestrial material prevents a more precise Ar(E) being given; the tabulated Ar(E) value and uncertainty should be applicable to normal material.

Source: Pure and Applied Chemistry 78, no. 11 (2005): 2051--66. © IUPAC (International Union of Pure and Applied Chemistry).